What is the vehicle year, make, model?
What is the child's age, weight, height?
If you do a search within this forum you'll read why I personally would not use the AO & it's never 1 of the seats I suggest parents consider.... However, many vehicles do require a pool noodle to achieve proper recline for infants -- the pool noodle will not compress over time like rolled up towels -- click the last link in my signature to find your local CPST to get help acheiving proper installation
